There have been an increasing number of opportunities in which cutting is performed on difficult-to-machine materials, such as titanium alloys used for aircraft parts, etc., as well as nickel-based heat-resistant alloys and cobalt-based heat-resistant alloys used for turbine blades for electric generators. In the cutting of difficult-to-machine materials with low thermal conductivity, such as nickel-based heat-resistant alloys and cobalt-based heat-resistant alloys, the cutting temperature is prone to become high. In such high-temperature machining, the strength of the cutting edge of a cutting tool is reduced, thereby leading to the occurrence of fracturing, so that the tool life will be extremely short compared to that involved in the past machining of general steel. In view of this, in order to achieve the long life of a cutting tool even when cutting difficult-to-machine materials, there has been a need to enhance the high-temperature strength of the cutting tool.
For example, Patent Document 1 proposes a method of controlling, in a cemented carbide, an average particle size ratio between a carboxide containing Zr and a complex carbide containing Zr and W, and thereby improving the high-temperature strength of the cemented carbide.